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Sources of Light
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Incandescence: light emitted from a hot body (a heated filament) due to its temperature
Example: incandescent lightbulb (very ineffiecient, ~95% energy used as heat)
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Bioluminescence: light produced and emitted by living organisms, as a result of a chemical reaction in which chemical energy is converted to light energy Examples: fireflies, glow worms, angler fish
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Chemiluminescence: light produced from a chemical reaction without a rise in temperature.
Example: glow sticks, “Glo” necklace
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Fluorescence: light produced by the absorption of radiation of one wavelength (colour), followed by immediate re-radiation, usually at a different wavelength Example: CFLs (compact fluorescent lights) – more efficient than incandescent, ~80% energy used as heat
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Phosphorescence: light energy is stored and then re-emitted slowly over a long time.
Example: glow in the dark toys.
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Triboluminsecence: light produced by friction or crushing.
Example: packing/duct tape, quartz crystals, Wintogreen Lifesaver mints.
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Light-emitting Diode (LEDs) small electric current causes semiconductor materials to emit light (electrical energy converted into light energy) Example: LED lightbulbs, Christmas lights
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Electric Discharge: electric current passed through air or a gas.
Example: lightning, neon signs, plasma ball.
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